Graphite Node Graph

I have been working with Keavon and TrueDoctor to integrate the node graph with Graphite, an open source web based graphics editor. Modifying images with the node graph (seen in the bottom of the screenshot) allows the user to try out different image operations, and easily modify them later, or to reorder them. This is in contrast to destructive image editors such as Photoshop, which directly modify the image data, meaning that in order to change an operation you have to undo it and then reapply it. Some of my changes are listed below:

• Integrate the node graph as a Node Graph Frame layer type - this allows the node graph to be stored in the editor and run.
• Add a basic API and rudimentary frontend for node graph layers - this integrated the rust data types with the frontend that Keavon had designed.
• Add some additional image effect nodes - some simple image effects such as the brightness and contrast node and the exposure node were added. These have later been improved by a number of contributors.
• Node code cleanup for vector data, and add node creation guide - this PR added some support for vector data in the node graph, and also improved documentation of the node creation process, allowing new contributors to more easily add a new node, which I've updated in Update node guide.
• Migrate vector data and tools to use nodes - This modified all of the vector tools like the rectangle tool to produce a node graph.

I'm continuing to work on improving the node graph in Graphite. These current changes can be seen in the live preview at editor.graphite.rs/